Earlier quoted context omitted.
You are militantly missing my point. There is no evidence that they are seeing message contents. All we are going on in this thread is the supposition that because they're getting "10 gigabytes a day", it must be message contents.
They themselves use the phrase "raw data" to describe what they collect (as "metrics"). Metrics are not comprised of raw data, but of measurements, so unless they're being hinky with word choice, a plain reading of their own materials would suggest that they do indeed receive user content.
Their own words are not dispositive; I'm not suggesting that they are. But here you're trying to interpret their words in a way that contradicts their own direct statement. Your interpretation is possibly accurate, but implausible.